The proposed study is the third in a series of randomized controlled trials to develop, evaluate, and diffuse an effective school-based smoking prevention curriculum. The first two studies established efficacy; the focus of the proposed research is evaluation of program implementation and effectiveness, as a function of provider and training variables. Secondary objectives for this Demonstration and Education research include: (a) a test of the hypothesis that higher levels of implementation will be associated with better outcomes, (b) preparation for diffusion of a complete set of curriculum, provider training, and implementation evaluation methods and materials, and (c) study of the effects of school environment on program effectiveness. A 2x2 factorial design will compare two types of provider (teacher & school nurse) and two training methods (print materials versus workshop training) with each other and a fifth, no treatment comparison condition. The proposed project will randomly select and randomly assign 100 schools, 20 per condition and some 7,500 youth in all, from six school districts. Schools will be stratified before randomization on factors affecting smoking prevalence. Study participants will be recruited when they are 11-12 years old, in Grade 6. The curriculum will be delivered to all volunteers in each intervention school in Grades 6, 7 and 8. All participants will be tested three times: midway through Grade 6 before the curriculum begins, and at the end of Grades 7 and 8. The primary end point will be self- reported smoking status on the Grade 8 followup, two-and-a-half years after the curriculum begins. The validity of smoking reports will be enhanced with the collection of breath carbon monoxide samples from all subjects at all test points. A comprehensive implementation evaluation will assess the relationship between implementation and outcome, to provide direct measures of training effects, and to develop a feasible implementation evaluation methodology for future diffusion studies.